Project Summary In eukaryotic cells, ultra-violet radiation (UVR) induces the formation of free radicals which damage cellular lipids, proteins and nucleic acids. In man this damage can lead to chronic inflammation and skin neoplasias, so that compounds which protect cells from UVR are of therapeutic interest. Flavonoids are candidates because they protect plant cells by absorbing UVR, and acting as free radical scavengers (FRS). Bluegrass Advanced Materials (BAM) has licensed a technology from Naprogenix Inc., which is based on the discovery that methoxylated flavonoids purified from extracts of a native goldenrod (Solidago nemoralis) have agonist activity at human alpha7-nicotinic receptors (nicAChRs). These receptors inhibit release of inflammatory mediators from skin macrophages which contribute to UV-mediated inflammation and carcinogenesis. In support, collaborative research with the University of Kentucky showed that a flavonoid-enriched goldenrod extract potently protected transgenic ?humanized? mice against UVR-induced inflammation and damage in vivo. However, the potential therapeutic and commercial value of this activity is limited by the modest persistence and bioavailability of these flavonoids when applied topically. To overcome this drawback BAM will utilize its proprietary technology to convert flavonoids into biodegradable polymer microparticles. These slowly release the original flavonoids from the polymer, essentially providing an extended release topical preparation with improved bioavailability. This phase I application will apply this technology to the methoxylated anti-inflammatory flavonoids and evaluate their microparticle preparation for UV- protection when administered topically in a mouse model of the fair-skinned, UV-sensitive human. The first specific aim is to prepare microparticle polymers of (a) the flavonoid-enriched extract of goldenrod and (b) pure rhamnetin, the methoxylated flavonoid with greatest potency on alpha7- nicAChRs. The second specific aim is to test each of these preparations for their ability to penetrate and protect humanized mouse skin against UVR, specifically measuring the tissue content of pro- and anti-inflammatory mediators, and measuring effects on erythema and inflammation. The effects of the microparticle polymers will be compared with those of the free flavonoids applied topically in ethanol /polyethylene glycol as used previously. If, as predicted, the UVR-protectant effects of the flavonoids are enhanced, then phase II will aim to (a) relate efficacy to alpha7-nicAChR activity using selective antagonists, and alpha7-nicAChR ?knockout? mice (b) test the effects of chronic use of the preparations on UVR-induced changes in mouse skin (c) develop new ways of producing these flavonoids. The ultimate objectives of phase I and II are to develop these methoxylated flavonoid polymer preparations as therapeutic and cosmeceutical agents. The intention is to commercialize these products in phase III in partnership with major pharmaceutical and cosmetics companies.